diff --git a/README.md b/README.md
index cfa830e..e4213d7 100644
--- a/README.md
+++ b/README.md
@@ -1,6 +1,6 @@
 # TODO
-- macro button design + package
 - UI button
+- macro button design + package
 
 - 
 # Actor Sheet Locker for Foundry VTT
diff --git a/src/actor-sheet-locker/lang/de.json b/src/actor-sheet-locker/lang/de.json
index 07c0144..ffbf06f 100644
--- a/src/actor-sheet-locker/lang/de.json
+++ b/src/actor-sheet-locker/lang/de.json
@@ -54,6 +54,9 @@
       "gmMsgSheet": "[{userName}] versucht, den Akteur [{sheetName}] zu verändern.",
       "gmMsgItem": "[{userName}] versucht, auf einem Charakterbogen den Item [{itemName}] hinzuzufügen oder zu ändern.",
       "gmMsgItemDeleted": "[{userName}] versucht, auf einem Charakterbogen den Item [{itemName}] zu löschen."
+    },
+    "controlButton": {
+      "label": "Actor Sheet Locker ein- und ausschalten"
     }
   }
 }
diff --git a/src/actor-sheet-locker/lang/en.json b/src/actor-sheet-locker/lang/en.json
index d98e626..fdb66df 100644
--- a/src/actor-sheet-locker/lang/en.json
+++ b/src/actor-sheet-locker/lang/en.json
@@ -54,6 +54,9 @@
       "gmMsgSheet": "[{userName}] is attempting to modify actor [{sheetName}].",
       "gmMsgItem": "[{userName}] is attempting to create or change item [{itemName}] in character sheet.",
       "gmMsgItemDeleted": "[{userName}] is attempting to delete item [{itemName}] from character sheet."
+    },
+    "controlButton": {
+      "label": "Toggle Actor Sheet Locker on/off"
     }
   }
 }
diff --git a/src/actor-sheet-locker/scripts/main.js b/src/actor-sheet-locker/scripts/main.js
index e2d49f4..eff362e 100644
--- a/src/actor-sheet-locker/scripts/main.js
+++ b/src/actor-sheet-locker/scripts/main.js
@@ -27,34 +27,38 @@ let permanentUIMsgID;
             Logger.info(Config.data.modDescription);
             if (Config.setting('isActive')) {
                 ActorSheetLocker.switchOn();
-                ActorSheetLocker.stateChangeUIMessage();
+                stateChangeUIMessage();
             } else {
                 ActorSheetLocker.switchOff();
             }
         });
 
         Hooks.on("preCreateItem", function (item, data, options, userid) {
-            return ActorSheetLocker.onItemChangedInSheet(item, data, options, userid);
+            return onItemChangedInSheet(item, data, options, userid);
         });
         Hooks.on("preCreateActiveEffect", function (item, data, options, userid) {
-            return ActorSheetLocker.onItemChangedInSheet(item, data, options, userid);
+            return onItemChangedInSheet(item, data, options, userid);
         });
 
         Hooks.on("preUpdateActor", function (actor, data, options, userid) {
-            return ActorSheetLocker.onSheetChanged(actor, data, options, userid);
+            return onSheetChanged(actor, data, options, userid);
         });
         Hooks.on("preUpdateItem", function (item, data, options, userid) {
-            return ActorSheetLocker.onItemChangedInSheet(item, data, options, userid);
+            return onItemChangedInSheet(item, data, options, userid);
         });
         Hooks.on("preUpdateActiveEffect", function (item, data, options, userid) {
-            return ActorSheetLocker.onItemChangedInSheet(item, data, options, userid);
+            return onItemChangedInSheet(item, data, options, userid);
         });
 
         Hooks.on("preDeleteItem", function (item, options, userid) {
-            return ActorSheetLocker.onItemDeletedFromSheet(item, options, userid);
+            return onItemDeletedFromSheet(item, options, userid);
         });
         Hooks.on("preDeleteActiveEffect", function (item, options, userid) {
-            return ActorSheetLocker.onItemDeletedFromSheet(item, options, userid);
+            return onItemDeletedFromSheet(item, options, userid);
+        });
+
+        Hooks.on("getSceneControlButtons", (controls) => {
+            renderControlButton(controls);
         });
     }
 )
@@ -94,7 +98,7 @@ async function initExposedClasses() {
     window.ActorSheetLocker = ActorSheetLocker;
     Hooks.on("updateSetting", async function (setting) {
         if (setting.key.startsWith(Config.data.modID)) {
-            ActorSheetLocker.onGameSettingChanged();
+            onGameSettingChanged();
         }
     });
     Logger.debug("Exposed classes are ready");
@@ -102,20 +106,200 @@ async function initExposedClasses() {
 
 async function initSocketlib() {
     socket = socketlib.registerModule(Config.data.modID);
-    socket.register("stateChangeUIMessage", ActorSheetLocker.stateChangeUIMessage);
-    socket.register("sheetEditGMAlertUIMessage", ActorSheetLocker.sheetEditGMAlertUIMessage);
-    socket.register("itemChangedGMAlertUIMessage", ActorSheetLocker.itemChangedGMAlertUIMessage);
-    socket.register("itemDeletedGMAlertUIMessage", ActorSheetLocker.itemDeletedGMAlertUIMessage);
+    socket.register("stateChangeUIMessage", stateChangeUIMessage);
+    socket.register("sheetEditGMAlertUIMessage", sheetEditGMAlertUIMessage);
+    socket.register("itemChangedGMAlertUIMessage", itemChangedGMAlertUIMessage);
+    socket.register("itemDeletedGMAlertUIMessage", itemDeletedGMAlertUIMessage);
     Logger.debug(`Module ${Config.data.modID} registered in socketlib.`);
 }
 
+function renderControlButton(controls) {
+    if (game.user.isGM) {
+        let tokenControls = controls.find(control => control.name === "token")
+        tokenControls.tools.push({
+            name: "toggleActorSheetLocker",
+            title: Config.localize('controlButton.label'),
+            icon: "fa-solid fa-user-lock", // see https://fontawesome.com/search?o=r&m=free
+            toggle: true,
+            active: Config.setting('isActive'),
+            onClick: (active) => {
+                Config.modifySetting('isActive', active);
+            }
+        });
+    }
+}
+
+function onSheetChanged(actorOrItem, data, options, userid) {
+    Logger.debug("actorOrItem:", actorOrItem);
+    Logger.debug("data: ", data);
+    Logger.debug("options: ", options);
+    Logger.debug("userid: ", userid, "game.user.id: ", game.user.id);
+    if (Config.setting('isActive') && (!game.user.isGM || Config.setting('lockForGM'))) {
+        if (!ActorSheetLocker.isSilentMode) {
+            ui.notifications.error("[" + Config.data.modTitle + "] " + Config.localize('sheetEditRejected.playerMsg'), {
+                permanent: false,
+                localize: false,
+                console: false
+            });
+            if (Config.setting('alertGMOnReject')) {
+                socket.executeForAllGMs("sheetEditGMAlertUIMessage", game.users.get(userid)?.name, actorOrItem.name);
+            }
+        } else {
+            ActorSheetLocker.isSilentMode = false;
+        }
+        return false;
+    }
+}
+
+function onItemChangedInSheet(item, data, options, userid) {
+    Logger.debug("item:", item);
+    Logger.debug("data: ", data);
+    Logger.debug("options: ", options);
+    Logger.debug("userid: ", userid, "game.user.id: ", game.user.id);
+    if (Config.setting('isActive') && (!game.user.isGM || Config.setting('lockForGM'))) {
+
+        // check if event is allowed
+        if (
+            data?.system?.worn != null
+        ) return true;
+
+        if (!ActorSheetLocker.isSilentMode) {
+            ui.notifications.error("[" + Config.data.modTitle + "] " + Config.localize('sheetEditRejected.playerMsg'), {
+                permanent: false,
+                localize: false,
+                console: false
+            });
+            if (Config.setting('alertGMOnReject')) {
+                socket.executeForAllGMs("itemChangedGMAlertUIMessage", game.users.get(userid)?.name, item.name);
+            }
+        } else {
+            ActorSheetLocker.isSilentMode = false;
+        }
+        return false;
+    }
+}
+
+function onItemDeletedFromSheet(item, options, userid) {
+    Logger.debug("item:", item);
+    Logger.debug("options: ", options);
+    Logger.debug("userid: ", userid, "game.user.id: ", game.user.id);
+    if (Config.setting('isActive') && (!game.user.isGM || Config.setting('lockForGM'))) {
+        if (!ActorSheetLocker.isSilentMode) {
+            ui.notifications.error("[" + Config.data.modTitle + "] " + Config.localize('sheetEditRejected.playerMsg'), {
+                permanent: false,
+                localize: false,
+                console: false
+            });
+            if (Config.setting('alertGMOnReject')) {
+                socket.executeForAllGMs("itemDeletedGMAlertUIMessage", game.users.get(userid)?.name, item.name);
+            }
+        } else {
+            ActorSheetLocker.isSilentMode = false;
+        }
+        return false;
+    }
+}
+
+function onGameSettingChanged() {
+    ActorSheetLocker.isActive = Config.setting('isActive');
+
+    if (game.user.isGM && Config.setting('notifyOnChange')) {
+        // UI messages should only be triggered by the GM via sockets.
+        // This seems to be the only way to suppress them if needed.
+        if (!ActorSheetLocker.isSilentMode) {
+            socket.executeForEveryone("stateChangeUIMessage");
+        } else {
+            ActorSheetLocker.isSilentMode = false;
+        }
+    }
+
+    // Refresh scene control button to reflect new state of "isActive".
+    ui.controls.controls.find(control => control.name === "token").tools.find(tool => tool.name === "toggleActorSheetLocker").active = ActorSheetLocker.isActive;
+    ui.controls.render();
+}
+
+function stateChangeUIMessage() {
+    let message =
+        (ActorSheetLocker.isActive ? Config.localize('onOffUIMessage.whenON') : Config.localize('onOffUIMessage.whenOFF'));
+
+    if (Config.setting('notifyOnChange')) {
+
+        let isPermanent = (
+            ActorSheetLocker.isActive &&  Config.setting('notifyPermanentlyWhileLOCKED')
+            ||
+            !ActorSheetLocker.isActive &&  Config.setting('notifyPermanentlyWhileUNLOCKED')
+        );
+
+        // Clear previous permanent msg (if any)
+        if (permanentUIMsgID != null) {
+            ui.notifications.remove(permanentUIMsgID);
+        }
+
+        if (ActorSheetLocker.isActive) {
+            permanentUIMsgID = ui.notifications.error(`[${Config.data.modTitle}] ${message}`, {
+                permanent: isPermanent,
+                localize: false,
+                console: false
+            });
+        } else {
+            permanentUIMsgID = ui.notifications.info(`[${Config.data.modTitle}] ${message}`, {
+                permanent: isPermanent,
+                localize: false,
+                console: false
+            });
+        };
+        if (!isPermanent) permanentUIMsgID = null;
+    }
+    Logger.info(message);
+}
+
+function sheetEditGMAlertUIMessage(userName, sheetName) {
+    let message =
+        Config.localize('sheetEditRejected.gmMsgSheet')
+            .replace('{userName}', userName)
+            .replace('{sheetName}', sheetName);
+    ui.notifications.error(`[${Config.data.modTitle}] ${message}`, {
+        permanent: false,
+        localize: false,
+        console: false
+    });
+    Logger.warn(message);
+}
+
+function itemChangedGMAlertUIMessage(userName, itemName) {
+    let message =
+        Config.localize('sheetEditRejected.gmMsgItem')
+            .replace('{userName}', userName)
+            .replace('{itemName}', itemName);
+    ui.notifications.error(`[${Config.data.modTitle}] ${message}`, {
+        permanent: false,
+        localize: false,
+        console: false
+    });
+    Logger.warn(message);
+}
+
+function itemDeletedGMAlertUIMessage(userName, itemName) {
+    let message =
+        Config.localize('sheetEditRejected.gmMsgItemDeleted')
+            .replace('{userName}', userName)
+            .replace('{itemName}', itemName);
+    ui.notifications.error(`[${Config.data.modTitle}] ${message}`, {
+        permanent: false,
+        localize: false,
+        console: false
+    });
+    Logger.warn(message);
+}
+
+
 /**
  * Public class for accessing this module through macro code
  */
 export class ActorSheetLocker {
-    static #isActive = false;
+    static isActive = false;
     static #previousState;
-    static #isSilentMode;
+    static isSilentMode;
 
     static healthCheck() {
         alert(`Module '${Config.data.modTitle}' says: '${ready2play ? `I am alive!` : `I am NOT ready - something went wrong:(`}'` );
@@ -142,11 +326,11 @@ export class ActorSheetLocker {
     }
 
     static isOn() {
-        return this.#isActive;
+        return this.isActive;
     }
 
     static isOff() {
-        return !this.#isActive;
+        return !this.isActive;
     }
 
     /**
@@ -156,170 +340,11 @@ export class ActorSheetLocker {
      * @returns {Promise<void>}
      */
     static async #switch(newStateIsON, silentMode = false) {
-        this.#isSilentMode = silentMode;
-        this.#previousState = this.#isActive;
+        ActorSheetLocker.isSilentMode = silentMode;
+        this.#previousState = this.isActive;
         // propagate change to the game settings, and wait for it to complete
         // It turned out to be much more stable here by waiting for game.settings to be updated.
         // Might be an ugly workaround, better ideas welcome!
         await Config.modifySetting('isActive', newStateIsON);
     }
-
-    static onSheetChanged(actorOrItem, data, options, userid) {
-        Logger.debug("actorOrItem:", actorOrItem);
-        Logger.debug("data: ", data);
-        Logger.debug("options: ", options);
-        Logger.debug("userid: ", userid, "game.user.id: ", game.user.id);
-        if (Config.setting('isActive') && (!game.user.isGM || Config.setting('lockForGM'))) {
-            if (!this.#isSilentMode) {
-                ui.notifications.error("[" + Config.data.modTitle + "] " + Config.localize('sheetEditRejected.playerMsg'), {
-                    permanent: false,
-                    localize: false,
-                    console: false
-                });
-                if (Config.setting('alertGMOnReject')) {
-                    socket.executeForAllGMs("sheetEditGMAlertUIMessage", game.users.get(userid)?.name, actorOrItem.name);
-                }
-            } else {
-                this.#isSilentMode = false;
-            }
-            return false;
-        }
-    }
-
-    static onItemChangedInSheet(item, data, options, userid) {
-        Logger.debug("item:", item);
-        Logger.debug("data: ", data);
-        Logger.debug("options: ", options);
-        Logger.debug("userid: ", userid, "game.user.id: ", game.user.id);
-        if (Config.setting('isActive') && (!game.user.isGM || Config.setting('lockForGM'))) {
-
-            // check if event is allowed
-            if (
-                data?.system?.worn != null
-            ) return true;
-
-            if (!this.#isSilentMode) {
-                ui.notifications.error("[" + Config.data.modTitle + "] " + Config.localize('sheetEditRejected.playerMsg'), {
-                    permanent: false,
-                    localize: false,
-                    console: false
-                });
-                if (Config.setting('alertGMOnReject')) {
-                    socket.executeForAllGMs("itemChangedGMAlertUIMessage", game.users.get(userid)?.name, item.name);
-                }
-            } else {
-                this.#isSilentMode = false;
-            }
-            return false;
-        }
-    }
-
-    static onItemDeletedFromSheet(item, options, userid) {
-        Logger.debug("item:", item);
-        Logger.debug("options: ", options);
-        Logger.debug("userid: ", userid, "game.user.id: ", game.user.id);
-        if (Config.setting('isActive') && (!game.user.isGM || Config.setting('lockForGM'))) {
-            if (!this.#isSilentMode) {
-                ui.notifications.error("[" + Config.data.modTitle + "] " + Config.localize('sheetEditRejected.playerMsg'), {
-                    permanent: false,
-                    localize: false,
-                    console: false
-                });
-                if (Config.setting('alertGMOnReject')) {
-                    socket.executeForAllGMs("itemDeletedGMAlertUIMessage", game.users.get(userid)?.name, item.name);
-                }
-            } else {
-                this.#isSilentMode = false;
-            }
-            return false;
-        }
-    }
-
-    static onGameSettingChanged() {
-        this.#isActive = Config.setting('isActive');
-
-        if (game.user.isGM && Config.setting('notifyOnChange')) {
-            // UI messages should only be triggered by the GM via sockets.
-            // This seems to be the only way to suppress them if needed.
-            if (!this.#isSilentMode) {
-                socket.executeForEveryone("stateChangeUIMessage");
-            } else {
-                this.#isSilentMode = false;
-            }
-        }
-    }
-
-    static stateChangeUIMessage() {
-        let message =
-            (ActorSheetLocker.#isActive ? Config.localize('onOffUIMessage.whenON') : Config.localize('onOffUIMessage.whenOFF'));
-
-        if (Config.setting('notifyOnChange')) {
-
-            let isPermanent = (
-                ActorSheetLocker.#isActive &&  Config.setting('notifyPermanentlyWhileLOCKED')
-                ||
-                !ActorSheetLocker.#isActive &&  Config.setting('notifyPermanentlyWhileUNLOCKED')
-            );
-
-            // Clear previous permanent msg (if any)
-            if (permanentUIMsgID != null) {
-                ui.notifications.remove(permanentUIMsgID);
-            }
-
-            if (ActorSheetLocker.#isActive) {
-                permanentUIMsgID = ui.notifications.error(`[${Config.data.modTitle}] ${message}`, {
-                    permanent: isPermanent,
-                    localize: false,
-                    console: false
-                });
-            } else {
-                permanentUIMsgID = ui.notifications.info(`[${Config.data.modTitle}] ${message}`, {
-                    permanent: isPermanent,
-                    localize: false,
-                    console: false
-                });
-            };
-            if (!isPermanent) permanentUIMsgID = null;
-        }
-        Logger.info(message);
-    }
-
-    static sheetEditGMAlertUIMessage(userName, sheetName) {
-        let message =
-            Config.localize('sheetEditRejected.gmMsgSheet')
-                .replace('{userName}', userName)
-                .replace('{sheetName}', sheetName);
-        ui.notifications.error(`[${Config.data.modTitle}] ${message}`, {
-            permanent: false,
-            localize: false,
-            console: false
-        });
-        Logger.warn(message);
-    }
-
-    static itemChangedGMAlertUIMessage(userName, itemName) {
-        let message =
-            Config.localize('sheetEditRejected.gmMsgItem')
-                .replace('{userName}', userName)
-                .replace('{itemName}', itemName);
-        ui.notifications.error(`[${Config.data.modTitle}] ${message}`, {
-            permanent: false,
-            localize: false,
-            console: false
-        });
-        Logger.warn(message);
-    }
-
-    static itemDeletedGMAlertUIMessage(userName, itemName) {
-        let message =
-            Config.localize('sheetEditRejected.gmMsgItemDeleted')
-                .replace('{userName}', userName)
-                .replace('{itemName}', itemName);
-        ui.notifications.error(`[${Config.data.modTitle}] ${message}`, {
-            permanent: false,
-            localize: false,
-            console: false
-        });
-        Logger.warn(message);
-    }
 }